Benchmarked: The Most Power-Efficient Ubuntu 19.04 Flavor Will Surprise You

Many of us are using laptops as our daily driver, so a Linux desktop OS that sips power is always a blessing. Ubuntu 19.04 delivers a serious improvement in power efficiency over 18.10 (check out the benchmarks here), thanks in part to optimizations in GNOME 3.32. But what's the most power efficient flavor of Ubuntu 19.04? After running a series of benchmarks via the Phoronix Test Suite and measuring system power consumption via the sys.power sensor, well, the answer surprised me. It'll probably surprise you as well!

5 flavors of Ubuntu 19.04 tested. Which is the most power efficient?

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After my experience with Xfce, I pegged that lean and lightweight desktop environment as the clear favorite. Certainly Xubuntu wins this contest, right? Or is there an underdog we should pay more attention to?

Let's jump into it.

The Benchmarking Process

It seems like very few laptops -- at least in my possession -- support the awesome sys.power sensor. Thankfully the Dell XPS 9370 does, so that's where my testing happened. This sensor allows you to record minimum, maximum and average system power consumption in milliwatts via Phoronix Test Suite (PTS). To do this on supported PCs, you simply issue your command preceded by "MONITOR=sys.power." So, if I want to benchmark Blender + see how long my machine takes to build a Linux kernel, the command will look like this:

You'll get not only the test results, but also a chart showing you power consumption during each test, complete with min/max/avg. Phoronix Test Suite will also show you cool stuff like Geometric Mean of all tests combined.

As I did with the Ubuntu 18.10 versus Ubuntu 19.04 benchmarks, I ran a small suite of "out-of-the-box" tests that measure CPU, disk and gaming performance. I tested Ubuntu 19.04, Kubuntu 19.04, Xubuntu 19.04, Ubuntu Budgie 19.04 and Ubuntu MATE 19.04 and, of course, measured system power consumption throughout. No CPU tuning was invoked, and no tweaks of any kind were applied.

Take a look at the results and then we'll get into some analysis below.

7Zip Compression

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7Zip Compression with System Power

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FLAC Encoding

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FLAC encoding with System Power

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FS-Mark Disk Test

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FS-Mark with System Power

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FS-Mark w/ 4 threads

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FS-Mark 4 threads with system power

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Timed Kernel Compilation

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Timed Kernel Compilation with System Power

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Super Tux Kart

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Super Tux Kart with System Power

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I debated whether or not to include the Ubuntu Budgie 19.04 results because of the comparatively high system power consumption. I'll ask that you take those specific results with a grain of salt for now. I'll also stress that PTS executes multiple runs of each benchmark to ensure accuracy and eliminate results (if any) that deviate too wildly.

I also did these benchmark runs multiple times using fresh installs with current updates, and did a sanity check by testing Solus Budgie and noticed similar results. I also reached out to Ubuntu Budgie developer Dustin Krysak, but working together we were unable to reproduce the results on his machine as it lacked the sys.power sensor.

That being said, I gleaned some insights from Canonical's Martin Wimpress (who also develops MATE). His reasoning is that while Budgie -- the desktop environment -- is based largely on GNOME, Ubuntu Budgie has additional features. The majority of them are written in Python. Wimpress explains that since Python is an interpreted language, it will cause the Python VM (interpreter) to tick and wake up the CPU.

At any rate, System76 is sending me an Oryx Pro laptop which I'm told supports sys.power. Once I receive it I'll run this entire suite again to compare and contrast.

UPDATE: I've tested Budgie 19.04 yet again and am finding far more sane, expected power readings. It's unclear what was throwing off the original tests, but I've included the updated results below and am actively working with the Budgie team to narrow down the issue.

Now, between distros like Ubuntu, Kubuntu and Xubuntu, we're seeing results you'd expect. Kubuntu with KDE is a bit more power-hungry. Ubuntu with its GNOME 3.32 implementation and in-house tweaks isn't winning the race, but performing admirably compared to 18.10 and its overall power usage is way more conservative. And then Xubuntu, which rocks the leaner Xfce desktop, is using a far slimmer power envelope than GNOME and KDE.

But you probably noticed something else in the mix: a surprise winner?

Check and MATE

System Power range for all tests (original)

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System Power range for all tests (updated)

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When plotting the system power range used across all tests, there is one clear winner: Ubuntu MATE. Not only that, but MATE is walking away from this particular test winning most of the performance benchmarks. What's going on here?

Martin Wimpress has this to say: "MATE is power efficient due to an aggregation of small margins." He explains to me that MATE was off the mark a few years ago, and he's since approached tuning MATE like you'd train an Olympic sprinter. "The margins between the competitors are so small there is no one thing you can improve to leap frog your opponents," he says. "So, you identify lots of small margins of improvement. Singularly they don't move the needle. Collectively, you win gold."

Geometric Mean of all test results

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As you can see from the above geometric mean of all test results, Ubuntu MATE 19.04 isn't winning gold in just power efficiency.

Because most people are using laptops these days, Wimpress says he's been plugging away at making MATE more power efficient. He also expects to see even stronger results with Ubuntu MATE 19.10. In the meantime, we can certainly enjoy the power improvements brought to the table.

From here, the best way forward is more exhaustive testing on multiple machines, adding tools like Powertop into the mix, and connecting the PCs to a Kill-A-Watt style device that can measure min/max/average wattage. The results above should not be considered conclusive, but they do warrant further, broader study.

If your PC hardware supports the sys.power sensor (you can check by downloading PTS and running "phoronix-test-suite system-sensors"), I encourage you to run a few tests of your own. Reach out to me on Twitter and let me know your findings!